Abstract:Complex solution system can be difficult to deal with by conventional solution chemistry calculation. In order to avoid this problem and investigate the influence of sodium silicate on the flotation of scheelite from fluorite, Newton-Raphson method was applied to solution chemistry calculation. And a new kind of species distribution diagram was drawn in terms of changing the total concentration of sodium silicate rather than the activity of silicate or hydrogen ion. According to the study of single-mineral flotation tests, electrokinetic measurements and species distribution diagrams, the selective surface precipitation of calcium silicate on the fluorite was identified to be the major depression mechanism of fluorite in the flotation of separating scheelite from fluorite using sodium silicate as the modifier and sodium oleate as the collector. X-ray photoelectron spectroscopic (XPS) analyses also provided strong evidence for this conclusion. The results show that the selective depression of scheelite flotation from fluorite can be achieved under conditions of moderate depression. The evaluated surface precipitation concentrations are in good agreement with the results of flotation experiments and XPS analysis results. This study also confirms that solution chemistry calculation with Newton-Raphson method has practical value in the interpretation and prediction of mineral flotation.

Key words: sodium silicate; fluorite; scheelite; solution chemical calculations; salt-type mineral flotation; XPS analysis